CEREAL EXPERIMENTS AT THE WILLISTON SUBSTATION. 



TEMPERATURE. 



The daily variations in temperature at Williston are recorded 

 automatically by a thermograph. These records are checked by the 

 use of maximum and 

 minimum thermome- 

 ters. The mean, max- 

 imum, and minimum 

 temperatures, by 

 months, during the 

 growing season for the 

 years 1909 to 1914, 

 inclusive, are shown 

 in Table IV. 



Table IV shows that 

 the highest monthly 

 mean temperature is 

 for July. This is the 

 only month that a 

 minimum lower than 

 32° F. has not occurred 

 in some one of the six 

 years. 



The frost-free period 

 is shown in graphic 

 form in figure 3, cover- 

 ing a period of 33 years 

 (1882 to 1914). It 

 shows that the average 

 i late of the last killing 

 frost in the spring is 

 May 18 and that the 

 avora^edateof the first 

 frosi in the autumn is 

 September 14. The 

 shortest period be- 

 tween frosts, as shown 

 by ill'- graph, was 80 



AVERAGE 



Fig. 3.— Diagram showing tho length of the frost-free period and the 

 average dates of the last killing frost in spring and tho first in 

 autumn for tho 33-year period from 1882 to 1914, inclusive, at the 

 Williston substation. 



905). 



he 



days (in L883) and the longest period was 155 days (in 

 average frost-free period for the 33 years is L19 days. 



Previous to L893, the temperature records were kept at Fort Buford 



and since that date at Williston. 



